Theme: 02. Assessing Remediation Effectiveness

Topic Area: 02b. Remedy Implementation: Assessing Performance and Costs

Formatted Title:

Remediation Plan for Contaminated Soils in a 43-Hectare Former PVC Plant in Israel

Background/Objectives:

The purpose of this work was to develop a sustainable soil and groundwater remediation plan for a site that was highly contaminated with mercury and chlorinated compounds in the north of Israel. The main objective of this project is to clean the site to a protective level for humans and the environment, while allowing the redevelopment of the site for commercial and residential use.

The site is a former PVC plant, located on the shoreline of the Mediterranean Sea, a few kilometers south of the city of Akko. The plant operated for about 50 years until it was abruptly shut down at the end of 2003 as a result of an explosion and fire. The soil and groundwater pollution on site was investigated for over 13 years since 2010 until to date, encompassing over 1,000 passive soil gas sampling points, dozens of active soil gas sampling wells, over 1,000 boreholes for soil sampling and hundreds of groundwater monitoring wells (groundwater level is ~2 meters below surface).

The findings show that the soil and groundwater are largely polluted with a combination of chlorinated solvents and mercury. Mercury in significant concentrations (reached over 15,000 mg/kg) was detected in the vicinity of the electrolysis plant and the drains around it, as well as inland disposal pits on the premise (mostly mercuric chloride). Methylmercury was found in minor amounts in the soil. The estimated amount of soil that need to be treated is about 225,000 tons.

Approach/Activities:

After an exhaustive review of the applicable methods for soil treatment, four methods of choice were selected for lab and field pilots:

Soil Washing- suitable for soil contaminated with mercury and/or chlorinated solvents with moderate concentrations- lab pilot was done in DEME research facility in Antwerp, Belgium.
Ex situ thermal treatment- suitable for soil contaminated with mercury and/or chlorinated solvents with moderate to high concentrations- included two pilots (both performed by Haemers technologies) – one at a lab scale and one in field scale (500 tons).
Bioremediation – suitable for soils contaminated with low to moderate level of chlorinated organic solvents.
Stabilization and Landfill in a Hazardous Waste landfill of soils contaminated with high levels of mercury.

Results/Lessons Learned:

All pilot tests met our expectations and the full-scale remediation plan included all four methods. Soil washing was found to be particularly effective in the sandy soil of the site (coarse beach sand) and very effective for mercury removal from soil with concentrations of up to 500 mg/ kg. This method is also cost effective and is expected to treat about 100,000 tons of soil. Bioremediation effectively reduced the concentrations of chlorinated solvents and is expected to treat about 100,000 tons of soil. Thermal desorption was found very effective for high concentrations of both mercury and chlorinated solvents, but due to its relatively higher cost, only 15,000 tons are planned to be treated thermally. Soil stabilization and landfilling in a hazardous waste site is the least sustainable and the most expensive treatment option, therefore only 10,000 tons of soil with the highest elemental mercury levels are planned for landfilling.

Before soil excavation, all buildings were sampled, demolished and crushed. Contaminated crushed material is intended for reuse in the thermal piles to replace clean gravel and will be reused on site after treatment.

Treated soil will be reused on site as a fill material as well as a fill material in a sound barrier that is planned in the south of the site.

This presentation will provide discussions concerning the basis of the soil treatment design, interpretation of and lessons learned from forthcoming (late 2023 through early 2024) data.

Stany Pensaert

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(Group 1, Poster Board #45) Remediation Plan for Contaminated Soils in a 43-Hectare Former PVC Plant in Israel